THE ROLE OF GRANZYME B-EXPRESSING CD8-POSITIVE T-CELLS IN APOPTOSIS OF KERATINOCYTES IN LICHEN-PLANUS

Epidermal basal cell injury with colloid body formation is a character istic feature of lichen planus, Infiltrated cells are thought to be re sponsible for the epidermal injury, Ultrastructural findings of colloi d bodies are typical of apoptosis. Granzymes in cytotoxic T lymphocyte s are involved in apoptosis probably together with perforin. Based on this background, we analyzed the role of granzyme B in the mechanisms of epidermal injury in lichen planus. On electron microscopy, basal an d suprabasal cells showed condensed chromatin and fragmented nuclei wh ich are typical morphological features of apoptosis, Nuclei of colloid bodies were positively stained by the in situ nick end labeling techn ique indicating that colloid bodies are subsequently formed in the pro cess of apoptosis, Immunohistochemical staining showed CDS-positive in filtrating cells to contain granzyme B, Cells undergoing exocytosis al so contained granzyme B, By immunoelectron microscopy, granzyme B mole cules were observed to be secreted from a lymphocyte to an apoptotic k eratinocyte. These findings suggest that granzyme B-positive CDS cells seem to induce apoptosis of keratinocytes in lichen planus.